All guides, page 11 of 20

Newest first. Search or pick a topic.

476 guides, newest first

• Payment Gateway API Design: From Intents to WebhooksBackend · A plain-English guide to payment gateway API design: payment intents, payment states, idempotency keys, signed webhooks and refunds, shown on one running example of a gateway for small Indian sellers.26 min read · Updated 22 Oct 2026
• PDF Parsing for RAG: How to Handle Tables, Scans and OCRAI and GenAI · A plain-English guide to PDF parsing for RAG: routing digital and scanned pages, fixing reading order, keeping tables whole and checking OCR, shown on one running example of a land-records office.30 min read · Updated 22 Oct 2026
• Design a Proximity Service: Nearby Restaurants at ScaleSystem design · A plain-English guide to proximity service design: geohash cells, the 9-cell search, Redis geo sets, replicas and caches, shown on one running example of a food app in Indore.24 min read · Updated 22 Oct 2026
• Query Rewriting for RAG: Multi-Query, Decomposition and HyDEAI and GenAI · A plain-English guide to query rewriting in RAG: simple cleanup and chat-history rewrites, multi-query search, decomposition, step-back questions and HyDE, built on one running electronics store example.22 min read · Updated 22 Oct 2026
• Raft Consensus Explained: Leader Election and Log ReplicationSystem design · A plain-English guide to Raft consensus: state machine replication, leader election, log replication, safety, stale reads and pre-vote, shown on one running example of a config store.29 min read · Updated 22 Oct 2026
• RAG Access Control: Permission-Aware Retrieval ExplainedAI and GenAI · A plain-English guide to RAG access control: how to stop an internal AI assistant from retrieving documents a user could not open, shown on one running example of a steel company's staff assistant.24 min read · Updated 22 Oct 2026
• RAG Evaluation Metrics: Recall@k, MRR and Context PrecisionAI and GenAI · A plain-English guide to measuring a RAG system in two halves, retrieval and generation, with worked numbers for most metrics, built on one running income-tax help assistant example.24 min read · Updated 22 Oct 2026
• RAG Reranking: Cross-Encoders Explained SimplyAI and GenAI · A plain-English guide to RAG reranking: bi-encoders vs cross-encoders, how many chunks to fetch and keep, cost, speed and measuring the gain, shown on one running example of a train-travel help bot.23 min read · Updated 22 Oct 2026
• Reasoning Models Explained: Thinking Tokens and When They PayAI and GenAI · A plain-English guide to reasoning models, built on one running maths tutoring example, covering thinking tokens, training, thinking budgets, cost, routing and how to test whether the extra thinking pays.22 min read · Updated 22 Oct 2026
• REST vs GraphQL vs gRPC: Pick a Style Per Use CaseBackend · A plain-English guide to REST, GraphQL and gRPC: how each works, what each costs, and how to pick one per caller, built on one running rental-listings example.26 min read · Updated 22 Oct 2026
• Retry, Backoff and Jitter: How to Avoid a Retry StormSystem design · A plain-English guide to retries, exponential backoff and jitter, and how to avoid causing a retry storm, shown on one running example of a weather data API.19 min read · Updated 22 Oct 2026
• Sagas: Distributed Transactions Without 2PCSystem design · A plain-English guide to the saga pattern, covering compensating steps, step order, safe retries and isolation gaps, built on one running online shop example.23 min read · Updated 22 Oct 2026
• Semantic Caching for LLM Apps: Reuse Answers Without Wrong HitsAI and GenAI · A plain-English guide to semantic caching for LLM apps: similarity thresholds, safe cache keys, expiry and false hits, shown on one running example of an electricity supplier's help bot.25 min read · Updated 22 Oct 2026
• Sharding Strategies: Range, Hash, Directory and Hot KeysSystem design · A plain-English guide to range, hash and directory sharding, choosing a shard key and fixing hot keys, built on one running example of a music streaming app.28 min read · Updated 22 Oct 2026
• Short Video App System Design: Infinite Feed and PrefetchingSystem design · A plain-English guide to designing a short-video feed: endless paging, prefetching the next swipe and fast-starting segments, shown on one running example of a dance-video app.23 min read · Updated 22 Oct 2026
• System Design Interview Framework: A Repeatable 45-Minute PlanInterview prep · A plain-English guide to the system design interview framework: a 45-minute plan from requirements to trade-offs, shown on one running mock interview for a shipment tracking service.22 min read · Updated 22 Oct 2026
• Tool Design for AI Agents: Descriptions, Errors and RetriesAI and GenAI · A plain-English guide to designing tools an AI agent can use well: names, descriptions, inputs, structured errors, safe retries, tool count and testing, built on one running ordering-agent example.24 min read · Updated 22 Oct 2026
• Two-Phase Commit and Its Problems: Why 2PC BlocksSystem design · A plain-English guide to two-phase commit, why it blocks when the coordinator fails, and what three-phase commit tries to fix, built on one running bank transfer example.24 min read · Updated 22 Oct 2026
• Design a Unique ID Generator (Snowflake): Sortable IDsSystem design · A plain-English guide to designing a unique ID generator like Snowflake, built on one running example of a Lucknow story-sharing app.26 min read · Updated 22 Oct 2026
• URL Shortener System Design: Keys, Redirects and ClicksSystem design · A plain-English guide to designing a URL shortener, from short keys and fast redirects to click analytics, built on one running SMS campaign example.24 min read · Updated 22 Oct 2026
• Webhook Design: Retries, Signatures and OrderingBackend · A plain-English guide to webhook design: retries, HMAC signatures, duplicates, ordering and safe URLs, shown on one running example of a freight-booking platform.23 min read · Updated 22 Oct 2026
• YouTube System Design: Upload, Transcode and StreamSystem design · A plain-English guide to designing a YouTube-like video platform, from resumable uploads to transcoding and adaptive streaming, shown on one running example of a regional video app.28 min read · Updated 22 Oct 2026
• Agent Harness Explained: The Code That Turns an LLM Into an AgentAI and GenAI · A plain-English guide to the agent harness: the prompts, tools, memory, guardrails and loop around a model, and why October 2026 research tunes the harness instead of the model, shown on one running example of an order-support agent.19 min read · Updated 22 Oct 2026
• Database Replication: Primary-Backup, Multi-Primary and QuorumsSystem design · A plain-English guide to database replication, from primary-backup and failover to multi-primary and quorums, built on one running payments ledger example.26 min read · Updated 22 Oct 2026